Compared to simple single-chamber pressure vessels or aerosol containers, the abovementioned pressure vessels with separate chambers have the advantage that they are able to dispense the substance in any spatial orientation, without the container first having to be shaken. A further advantage of these two-chamber containers is that no consideration has to be taken of possible chemical incompatibilities between the propellant and the substance.
Examples of such containers are, on the one hand, the spray containers which, in their interior comprise a flexible bag with the sprayable substance, and in which the propellant fills the space between this bag and the actual container. As the container is increasingly emptied of the sprayable substance, the bag is compressed by the action of the propellant, thus ensuring that the remainder of the sprayable substance is still pressurized. The term “bag in a can” is often used in this field for such containers. Examples of two-chamber containers of this first type available on the market at the date of filing of the present application are the containers sold by the Applicant of the present application under the trade names LamiPACK, COMPACK, MicroCOMPACK and AluCOMPACK. Other examples are the containers under the BiCan® brand from Crown Aerosols (England), the containers sold by the company EP Spray Systems SA (Switzerland) under the trade name “EP Spray”, and the containers available under the Sepro® brand from the United States Can Company.
Another category of such containers are those that are referred to in this field by the term “can-in-a—can”. Here, instead of the flexible bag, a second, inner can is provided which gradually collapses under the action of the propellant and as it increasingly empties.
A further category of two-chamber containers are the containers in which the propellant presses from underneath against a movable piston located in the container. This piston is typically arranged initially near the bottom of the container; the propellant is located in the space between the container bottom and the piston. The substance to be sprayed is located above the piston in the remaining space of the container. As the container is increasingly emptied of the sprayable substance, the piston slides upwards inside the container, under the action of the propellant, and thus ensures that the remaining portion of the sprayable substance is still pressurized. Pressure vessels of this kind comprising a piston are sold by the United States Can Company, for example.
The propellants used in the above-described two-chamber containers are typically gaseous carbon dioxide, air, nitrogen, liquefied gases, for example propane and butane, fluorochlorinated hydrocarbons or fluorinated hydrocarbons.
The solubility of carbon dioxide in POLYETHYLENE GLYCOL 400 was determined in an article (“ACS Symposium Series”, 2002, pages 166-180) in view of providing solvents for the catalytic reduction of carbon dioxide (for reducing greenhouse gases).
In another article (“Canadian Journal of Chemical Engineering” 83(2), 2005, pages 358-361), again in view of reducing the greenhouse gas carbon dioxide, the solubility of carbon dioxide in different ethers of different polyethylene glycols was examined.
The object of the present invention is to make available an improved pressure vessel of the above mentioned type.